Gem Ventilated disk brake kits

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

Hey Guys,

As some of you might know, I have been putting together a front brake upgrade package, consisting of a ventilated disk and standard gemini caliper, but with a spacer plate.

The rotor being ventilated, and the fact that it is a bigger diameter (250mm compared to standard 239mm) means a lot more energy/heat can be absorbed by the brake, before any brake fade occurs.

This type of upgrade would be ideal for weekend club sprints, rallys, etc. I am also confident that it will meet the braking performance requirements for VIC and NSW engineers certificates when transplanting a heavier engine, such as V6, etc.

Due to the use of the standard caliper, a change in brake bias is not an issue. Brake balance therefore remains as good as factory.

The installation is literaly a bolt in job. Undo nut retaining wheel bearing, slide hub off, unbolt standard rotor, bolt on ventilated rotor, unbolt caliper, seperate two halves, install spacers, bolt everything back together and bleed brakes.

Kits consist of:

2 x 250mm diameter ventilated disks - machined, drilled and tapped so bolts to standard gemini hub,
4 x laser cut caliper spacers - mount inside gemini caliper to allow fitment over ventilated disk, no modifications involved, simple bolt in procedure,
4 x genuine rubber seals for spacers,
8 x longer high tensile (grade 8 & 10) bolts for calipers to allow for spacer thickness
fitting instructions provided, simple to follow.

Prices are $190 using second hand rotors that are undersize, therefore probably wouldn't pass a roadworthy, but you could use them for racing, or if you didn't plan on needing a road worthy anytime soon, etc.

$220 using second hand rotors of at least legal thickness

$290 using brand new rotors.

I havn't got a price on slotted, or slotted and cross drilled, can get price on request, but if you consider, a pair of slotted disks are usually about $100 over standard, and cross drilled and slotted would be about $150 over price of standard pair, then thats the price that would be added to kit price.

If you want photos, let me know. Feel free to ask any questions, I am not trying to rip anybody off, or make a big dollar, I am just providing this kit for people that want it.

Ben Wight

Winterheart · tinkerer Joined: 04 Dec 2002 Posts: 144

I'm extremely interested. Will it still fit under 13" rims, or do we need to increase rim size? I'm guessing from your comments that it is all a bolt up proposition. I'm really really interested in photos too, could you send them to wynterhartt@hotmail.com please? What sort of cost would I be looking at for slotted and\or slotted crossdrilled as well? Cheers Smile

Loz · backyard mechanic Joined: 05 Oct 2001 Posts: 943

Have you already tried it?
How much clearance will there be between the outside rim of the rotor, and the inner surface of the caliper where the spacer will be? It couldnt be much if any, I would have thought that the caliper would need to have been moved out slightly to still use the gemini calipers?

ONLYA4 · petrol head Joined: 12 May 2003 Posts: 1114

Loz, my guess is that the caliper does need to be moved, as Ben said "standard gemini caliper, but with a spacer plate."
Could be wrong though.

gem12c · tinkerer Joined: 27 Mar 2002 Posts: 53

very intresting, what car does the 250mm rotor came from ? will the offset be affected ? if you can send me same photo's to sds_g75@yahoo.com.au.
finally some good research. good stuff ben.

Racegem · backyard mechanic Joined: 30 Jan 2002 Posts: 987

Ben, you don't mention the spacer for mounting the caliper further out to compensate for the larger disc.

Would you be willing to sell the spacers for the caliper spearately, and to tell us the origin of the new rotor (dba part no.)? Mainly to be able to replace the rotor when the old one wears out.
My mates Mazda 1300 race car apparently runs the same front caliper as factory fitment so he might be interested in doing the caliper spacer and sourcing our own rotor.

What do you reckon about the brake bias when used with the rear disc upgrade that Gene has done?

Cheers, Yonnee.

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

Hey guys, spacer goes in the cailper, to increase the 'gap' that the rotor moves through.

the caliper mounts in the standard position.

the hub diameter of the 250mm rotor is almost the same as the standard gemini rotor, so therefore clearance shouldn't be an issue.

However, I have not used this combination, I bought a similar setup and developed that idea. There were no signs of rubbing on the caliper. They were painted and no paint was missing/rubbed off!

In a worst case scenario, where clearance between caliper and rotor hub are tight, then the caliper may have to be ground on the corners by 1mm or so. This should be able to be easily done with a hand file, etc. Angle grinder would take about 2 seconds.

I dont have a spare stub axle to install the assembly to, but will check ASAP for those concerned. As I said though, if clearance is an issue, it wont be by much, and it will be easily rectified.

Ben

YTD20T · rice boy Joined: 19 Sep 2003 Posts: 28

hey man can you send me some pics
bradley.williams@cummins.com

murph · tinkerer Joined: 17 Apr 2002 Posts: 53

Im interesed in having alook the brakes, so could you send some pics to samurph84@yahoo.com, Are you going to get the set up checked by an engineer? Cos it would be good to know that they are legal and safe.

Loz · backyard mechanic Joined: 05 Oct 2001 Posts: 943

But you get where I mean?? It not the hub I was thinking about, it was the 250mm diameter part of the rotor. Now Im not sure how much clearance there is on the standard gemini brakes here, but Id say it would be pretty tight, so with the increased diameter rotor it would be diminished alot, I would even have though it would have hit, and whether or not grinding it away would work, as there might be a little bit too much material.
Anyway, if it clears then full credit to you.

TURBO TF · tinkerer Joined: 07 Apr 2003 Posts: 171

very interested may i please have a pic aswell? thanks ben!! bighayds_007@hotmail.com

DOHC_TF · tinkerer Joined: 11 Feb 2003 Posts: 123

Could u send sum this way plz...

monaro_man327@hotmail.com

cheers

HOP_A_LONG · tinkerer Joined: 27 Aug 2003 Posts: 274

I'd hate to tell you but its dissipating heat that increases a brakes affectiveness, not how much heat it absorbs.
Just a hint
HOP-A-LONG

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

Check your email

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

check your email